John Clarke (born 10 February 1942) is a British experimental physicist and Professor Emeritus at the University of California, Berkeley. He is known for his various works on measurement devices based on superconductivity. Steven Girvin has called Clarke "the godfather of superconducting electronics".
In the 1980s, Clarke led a research team, that included John M. Martinis and Michel Devoret. Their discoveries in macroscopic quantum phenomena using the Josephson effect earned them the Nobel Prize in Physics in 2025.